Yokogawa In-Situ Gas Analyzer TDLS200 - Manual (Page 6)

6
IM11Y01B01-12E-A
1st Edition
2 Installation
2.1 Process Measurement Point Considerations
The following criteria should be considered when selecting the installation point in respect to the
process conditions:
•
Process Gas Flow Conditions – Laminar, homogenous gas concentration distribution
conditions across the measurement point are recommended.
For circular ducts/stacks this condition is generally at least three unimpaired diameters (D)
before and after a process bend. For rectangular cross sections, the hydraulic duct
diameter (D) is derived from:
D = (4 x duct cross sectional area) / duct circumference
If neither situation exists or is possible, then distribution of the unimpaired section of duct
should be 66% on the inlet side and 34% on the outlet side.
Profiling of the proposed measurement point may be required to ensure that a correct
installation point is selected.
•
Process Gas Temperature – It is recommended that the analyzer be installed at a location
where temperature fluctuations are minimized. Generally as a guide, if the temperature of
the gas at the point where the analyzer is to be installed is to vary by more than +/-10
o C (+/-
18 o F) then an “Active” input signal should be used for compensation.
Ensure the analyzer has been selected and configured to suit the maximum operating gas
temperature.
• Process Gas Pressure – It is recommended that the analyzer be installed at a location
where pressure fluctuations are minimized. Generally as a guide, if the temperature of the
gas at the point where the analyzer is to be installed is to vary by more than +/-0.05Bar (+/-
0.725psi) then an “Active” input signal should be used for compensation.
Ensure the analyzer has been selected and configured to suit the maximum operating gas
pressure.
Ensure the process isolation windows have been selected and configured to suite the
maximum design gas pressure.
•
Process Dust/Particulate Matter – It is recommended that the analyzer be installed at a
location where dust loadings are minimized. Dust and other particulate matter will reduce
the optical transmission of the measuring laser beam. Within limits, the loss of optical
transmission does not affect the measurement however a Warning alarm will be initiated
when the transmission falls below allowable limits. The amount of dust loading is also
dependent upon the optical path length – Consult Factory for further details.